Process of recovering fine gold.



J. H, ALLIN'G. PROCESS OF RECOVERING FINE GOLD.

APPLICATION FILED MAY 4t, 1908.

Patentmi Feb. 1, 19M).

11V VEN TOR.

WITNESSES A TTORNE Y.

JAMES H. AIDLING, OF SAN FRANCISCO, CALIFORNIA.

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specification of Letters Patent.

Patented net. it, rain.

Application filed May a, 1908. Serial to. 450,695

To all whom it may concern:

' Be it known that I, JAMEs H. ALLING, a citizen of the United States, residing at San Francisco, in the county of San Francisco and State of California, have invented new and useful Improvements in Processes of Recovering Fine Gold, of which the fol lowing is a specification.

The object of the present invention is to provide a process for the recovery of very line particles of gold, silver, and platinum.

There are known to exist large natural deposits of gold-bearing material which are comparatively rich in the precious metal,

but from which the gold. /cannot be recovered by any known process except smelting; and as the cost of smelting 1S trom $5.00 to $7.00 a ton, besides the freight, the

cost by smelting is prohibitive except for very valuable ores. The reason why such gold cannot be recovered by ordinary methods is, either that the particles of gold are so extremely minute, that they float away, and cannot be arrested in the ordinary sluices, ainalgamators, and othenapparatusin general use, or that the particles of gold are incased in capsules of material which has to be removed by grinding, so that the particles of gold will be separated as free gold, and recovered by amalgamation. But, to do this the material must be ground to such a degree of fineness, say 100 mesh or smaller, that, in this case also, the

ordinary methods of recovering this very fine gold proves impracticable or too expensive. In addition, there are, in the States of California, Nevada and elsewhere, large deposits of tailings from former workings of ore, which tailings contain a large amount of gold, but in such a finely divided state as not to be recoverable by ordinary methods. Also many of these dumps, while containing finely divided gold, also contain such large quantities of copper, iron or arsenical pyrites, and other baser ores, that the ordinary cyan'id process cannot be profitably applied thereto, on account of the baser ores consuming too large a proportion of the cyanid. These can be worked by my process.

In the accompanying drawing, Figure 1 is a alanview, of the apparatus; Fig. 2 is a bro e11 side-view of the same; Fig. 3 is an enlarged broken detail longitudinal section of the same; Fig. t is a cross section on the line t-d of Iiig. 3'; Fig. '5 is an enlarged broken detail longitudinal section through an anode plate and mercury pocket.

Referring to thedrawing, 1 indicates a sluice box, which is sloped at a water angle than are the sluice boxes used %or the recovery of gold in the ordinary processes. In the bottom of said sluice box is a con tinuous amalgamating plate .2 formed at suitable intervals into pockets or. troughs 3. Each pocket is formed with a rear wall 4 having a considerable slope, nearly 45 de grees, to the vertical, a front wall 5 sloping slightly backward from the vertical, and a bottom substantially horizontal. In each pocket is placed a sulhcient quantity of mercury, shown at 7 The sides of the sluice box are formed with oblique grooves S; inclined rearwardly upward, an pcross said sluice box extend anode amalgamating plates 9, with their edges in said grooves. The lower edges of said plates extend to within a shortdistancc, say of an inch, from the upper surface of the mercury in the troughs or pockets .3. The height of each plate can be. adjusted by means of adj ustlng screws 10 screwed through lips 11; extending from the plates over the sides pt the sluice box, said screws resting on the tops of said sides.

Extending along one side of the sluice box is an electric conductor 13, connectedto the are rovided swingino carbon anodes 16 suspen ed from bars 1: extending across be? tween the tops of the sides of the sluice box, substantially midway between the anode plates 9. In certain cases, it may be desirable to interpose more than one swinging anode between each pair of anode plates. These cross bars 17 are electrically connected to thelongitudinal conductor 13.

The cathode plate 2. is connected by a wire 19 to the source of the electric current.

i The material, having been first finely pull verized, is fed by a chute 23' into the top all the sluice box; At the .sanre time therein fed, by apipe 242 .31 sufficient quantity of water, about 4 tons to 1 ton of material, and througha pipe 32 is fed a small proportion, about .1 to 1000, 2000, or more parts, of a mixture consisting of aqueous solutions of potassic cyanid and mercuric chlorid. The proportion of the mixtureto the water will vary according to the richness of the ma terial being treated, the rule being to supply,

I 1n the mercuric chlorid, one ounce of mercuryto each ounce of gold in the material. In treating certain ores, I have found satisfactory proportions by weight to be 1/2 to lb. of .potassic cyanid to 2 oz. mercuric chlorid and 5 gallons of the solution. The addition of the cyanid facilitates the electrolysis and cleans the gold. The electric current passes from the anode plates and swinging anodes into and through the water and other 'material flowing down thesluice box and enters the cathode plate 2 in the bottom of the sluice box, either directly, or through the mercury in the troughs or pockets 3 thereof. The density of the current used is comparatively low, being from 1/10 to 1 ampere for each square foot of cathode surface according to the richness of v the material.

pact of the particles of For the purpose of varying the amount of current for dlfierent material a rheostat 20 is provided. I have found a voltage of 5 volts to be satisfactory in practice, An ammeter 21 and volt meter 22 are used to indicate the current andvoltage.

By the above described process I have been able to save over'95 per centum of the values of material containing finely divided gold, which cannot be saved by ordinary processes.

It is in order to replenish the aqueous solution of mercuric chlori d with mercury that the surface of the anode is amalgamated and since the mercury is continually being removed from the rear surface of the anode plates by electrolysis, as well as by the imis desirable to replace this mercury as fast as removed, so that there Wlll always be a sufficient coating of mercury upon the anode; proper action of the ap- 1 plates to obtain a paratus. Many contrivances may be adopted for this purpose and I show herein the following. Upon the front or upper side of each anode plate is formed a narrow chamber 26,

' the rear wall of said chamber being formed by the anode plate itself, and the front wall 27 being parallel to said anode plate. This chamber is, at suitable intervals of time, supplied with mercury, and the mercury runs from said chamber through very minute perforations 28 in the anode plate to the rear wall thereof, on which it spreads immediately upon its emergence from said perforations, forming a thin film or coating upon the silvered surface of the plate. The mergold thereagainst, it i cury which tends tocollect at the bottom of each trough is drawn oil by an overflow pipe 29 running from the bottom of the trough and thence to the side of the apparatus and then upward to such a level, that when the mercury rises to a certain level in its trough it will overflow from said overflow pipe 29 into ,a conduit 30 leading to a receptacle 31. From this receptacle it can i or redistributed among the several mercury chambers. By this means the levels of the trou hs are maintained constant notwithstan ing the continual addition thereto of the mercury coming from the anode plates. Thus there is no loss whatever of mercury, and there can be no flouring of the mercury, on account of the electric current continually passing thcrcthrough.

A great advantage of the above described process over the ordinary process of cyaniding is the great saving in the cost of the plant required and the'time and labor consumed. For instance, whereas to cyanid a given amount of ore by the ordinary process of cyaniding would require a plant costing, say, $100,000, the same results can be ob-- tamed with my ing $10,000, and whereas the time required I for cyaniding a given amount of ore would,

in the cyaniding plant above referred to, be from 36 to 72 hours, the same amount of work by my improved process could be obltaincd by a continuous flow of about 10 hours, and with practically no cost for labor or manipulation, as compared with a considerable cost for labor expended in the cyanid plant, in addition to great expense for l skilled supervision and chemicals. l I claim 1. The method of recovering gold which consists in mixing the gold bearing material with a solution of a mercury salt, causing the mixture to flow between the upper and lower electrodes, and collecting the resulting amalgam at the bottom of the stream of the mixture, substantially as described.

2. The method of recovering gold which l consists in mixing the gold bearing material with water and a solution of a mercuric compound and. passing an electric current through the mixture from an anode having j a coating of mercury, and continually replenishing the mercury removed from the substantially as described. f In testimony whereof I have hereunto set my hand in the presence of two subscrlbmg witnesses. l

Witnesses:

FRANCIS M. Wmon'r, D. B. RICH/inns.

' anode,

process with a plant cost be removed from time to time and retorted 

